1. Field of the Invention
The present invention is directed to a method for transmitting items of information between mobile stations and a communication network, a communication network operating according to the method, and a mobile station operating according to the method.
2. Description of the Prior Art
Communication networks, for example the mobile radiotelephone network according to the GSM standard (Global System for Mobile Communication), enable communication connections to mobile stations of mobile subscribers via a radio interface. The communication network is provided with radio-based components in a radio-based subsystem and with switching-oriented means in a switching-based subsystem. The communication connections are set up, maintained and dismantled by transmitting and receiving items of signaling information and traffic information (e.g. in the form of speech or data) in both transmission directions via the radio interface. The access of the mobile subscribers to the communication network ensues by means of the mobile stations, which can communicate in wireless fashion with radio stations (base stations) arranged in distributed fashion at the network side.
During the commissioning (i.e., bringing "on line") of the mobile station into the communication network, only the basic characteristics of the mobile station, such as for example transmission power, encryption algorithm, support of a short message service, are transmitted. It is not known to the communication network whether a mobile subscriber whose SIM (Subscriber Identity Module) card is in principle cleared for particular services (e.g., data services or fax services) can also actually use these services. This has the consequence that, for example, telefax calls or data calls coming in from the communication network via the radio interface are provided to the mobile station in question by the call without insurance that a successful data transmission will occur between the communication network and the mobile station. This is because if the mobile station is not equipped with the additional device or devices necessary to receive the data, the data call cannot be accepted by the mobile station and the transmitted data cannot be made available as an output. The data call must thus be rejected by the mobile station, and corresponding signaling information must be sent back to the communication network. The lack of knowledge of the relevant technological possibilities at the mobile station for the use of additional services leads to an unnecessary network load, because resources have to be provided for the transmission of traffic information without resulting in a successful transmission of this information. This is particularly disadvantageous in communication networks with a radio interface, since the transmission capacity and the radio-based resources available via air are limited, and generally form a bottleneck in the transmission of information.